Proportional mask



Oct. 9, 1934. R., Q COCK 1,976,278

PROPORTIONAL MASK Filed June 12, 1928 2 sheets-sheet 1 I ZZ@ f4 5f E2G/'Z7 /f0.\ Z/Z Flag' Oct. 9, 1934. R. c. cooK 1,976,278

PROPORTIONAL MASK Filed June 12, 1928 2 Sheets-Sheet 2 l NVEN TOR.

A TTORNEY;

Patented Oct. 9, 1934 STATES raisers 'PATT f' ECE 12 Claims.

When a photograph or drawing is enlarged or reduced it often happens that the finished size does not correspond with the proportions of the original, thus making necessary the use of only such part of the original photograph or drawing as is proportional tothe shape of the finished enlargement or reduction. For example, the type page of certain magazines measures 5 X 7 inches. It is obvious that a photograph measuring 8X 10 inches cannot be reduced in its entirety to 5 X 7 inches-the proportions'or the two photographs being different. It is therefore necessary to determine which portion of the 8 X 10 picture can most advantageously be reduced to 5 X '7 inches.

Heretofore recourse has been had to slide rules or other devices which give the proportions of one size in terms or the other; another method Widely used is to draw the diagonal of the picture it is proposed to enlarge or reduce. Lines from any point on the diagonal and parallel to two adjoining sides oi the original picture make with the other two sides a rectangle proportional to the original, and thus indicate the sizes to which the original can be enlarged or reduced. All these r methods are relatively complicated and tedious and the present invention is designed to simplify and expedite the process above described.

The invention further contemplates in aproportional mask of the type above set forth, the provision of adjustable devices whereby the mask may be used for determining enlargements or reductions of different predetermined proportions, having such dimensions as 5" X 7", 4" X 7", and 3" X 7, it being understood that the mask is capable of being constructed in various sizes to meet instant requirements. With the above and other objects in View that will become apparent as the nature of the invention is better understood, the same consists in the novel construction, combination and arrangement of paws to be hereinafter more fully described and then claimed.

In the accompanying drawings which show preferred embodiments of the present invention,

Figure l is a top plan View of a proportional mask constructed in accordance with the present invention showing the mask plates at their-limits or expansive movement set at 5" X 7, and showing by dotted lines in fully retracted position, the plates set at 4" X 7,

Figure 2 is an edge elevational View of the mask,

Figure 3 is a detail sectional view taken on line 3--3 of Figure l,

Figure 4 is a cross-sectional View taken on line 4 4 of Figure 1 showing facial contact between the relatively thin ilat plate sections,

Figure 5 is a cross-sectional View taken on line 5--5 of Figure 1, and

Figure 6 is a plan View of modied form of movable mask plate.

The proportional mask disclosed herein is based on the principle that in any rectangular figure parallel to sides that meet on the diagonal subtend a larger or smaller ligure that is proportional to the original gure. In the device herein described, this is accomplished by having two masks comprising a pair or" plates made of stiff material such as sheet metal, cardboard, bre, Celluloid, or the like. One of the masks 10 which is intended to rest in a stationary position, is composed of a rectangular sheet of material having a rectangular aperture formed therein that is slightly larger than the largest picture it is proposed to enlarge or reduce. rIhe second mask ll which is movable relatively to the mask 10, is oi angle formation and comprises a pair of arms 11a and 1lb, with their inner edges perpendicular to each other and with the outer edges suitably rounded. lIhe arms of mask 1l are slightly longer than the adjoining sides of the rectangular .aperture in mask 10. By the provision of suitable guide means mask 11 is arranged to slide over mask 10 in such a manner that the two inner perpendicular edges 12 and 13 of mask 11 are always perpendicular to the adjoining sides 14 and 15 of mask 10, and so that the corner 16 of mask 11 travels on a radius of a circle having the corner 1'7, of the mask 10, as its center. The particular radius on which the corner 16 of mask 11 travels determines the proportions of the rectangle included between the two adjoining sides of mask l0 and the tWo adjoining sides of mask l1. Thus if the masks are arranged to make a rectangle 5 X '7 inches and the guide that controls the Ymotion of mask 11 is arranged parallel to diagonal of this rectangle, it is evident that all the rectangles generated by sliding mask 11 along these guides will be proportional to a rectangle measuring 5 X 7 inches, and any portion of a picture subtended by such proportional rectangles can be enlarged or reduced to 5 X 7 inches.

It is further evident that by altering the position of the guide controlling the motion of mask 11, so that it parallels other radii having their center at corner 17 of mask 10, and adjusting mask 11 so that its sides are normal to the adjoining sides of mask 10 and the corner 16 is on the radius to which the guide is parallel, the device can be arranged to determine enlarging sizes of rectangles having any proportion.

In practice I have found the arrangement illustrated in Figures 1 to 6 to be a convenientI application of these principles. The member for guiding mask l1, denoted by the numeral 18, is in the form of an arm set up from the mask plate 10 with one end depressed and pivoted to the mask 10 as at 19. On the guide member 18 is a slide 24 shown in detail in Figs. 1 and 2 to which the mask 11 is fastened by means of a pivot 20 and a screw passing through the arcuate slot' 24a in the slide and retained by the thumb nut 21, which is used to adjust mask 11 at different angles with reference to the slide and hold it rigid therewith. The point of attachment of the slide from the pivotal point 20 to the corner 16 of mask 11 is exactly the same as the distance between the point of attachment 19 of the fixed end of the guide 18 and the corner 17 of mask 10 as shown by dot anddash lines a and a. Furthermore mask 11 must be so arranged that when its sides 12 and 13 are normal to the adjoining sides 14 and 15 of mask 10 a line joining the corner 17 of mask 10 to the pivot on the guide 18 is parallel to a line joining the corner 16of mask 1l to the point 20 where the slide is pivoted to mask 11. In other words, the sliding of mask 11 on the guide 18 (the sides of the two masksv 12, 13--14, 15 being normal) can be relied on to generate proportional rectangles only if the figure described by lines drawn between the points 16, 17, 19, and 20 (dot and dash lines a a', b b) is a parallelogram with one side co-inciding with the axis of the guide 18.

The connection between the slide 24 and the guide 18 comprises a strip 24h at one edge of the slide that is bent to inclose the guide with a finger-piece 25 at one end thereby to facilitate manipulation of the mask plate 11.

The movable end of the guide member 18 is arranged to be clamped to mask 10 by a thumb nut in such a way that the pointer on the upper end of the guide 18 can be brought opposite various points on a graduated scale 22a on mask 10 which shows the various sizes to which it is proposed to enlarge or reduce a picture. The location 0f the points on this scale can be determined by setting the two masks at the sizes desired and marking on the scale on mask 10 the position of the marker on the slide 22.

The mask 10 is provided with an arcuate slot 10a centered on the guide pivot 19 with the opposite side of the slot 10a at the lower side of the mask grouted to accommodate insetting of the bolt and thumb nut 26, so that the device will lie flatly on a table or the like.

A stop 23 is also attached to mask 10 on the side opposite the guide. It must be exactly perpendicular to the adjoining side of the aperture in mask l.. This is for convenience in adjusting the masks so that their sides are normal as indicated by thedotted line position of the mask 11 in Fig. 1-. An inch scale 30 on the edges of the masks may be useful in some cases. Other arrangementsof the guide and movable mask can be made that will apply the same principle to produce a similar result. By a system of pivoted arms (a double parallelogram) the movable mask l1 could be arranged so that it would always be in the correct position with respect to mask 10, thus eliminata ing the clamp and the stop. It is held that for practical purposes the arrangement herein described is more desirable on account of its simplicity than an instrument having more moving parts.

The device is adjusted and used as follows: The pointer 22 on the movable end of the slide 18 is set at the size to which it is proposed to enlarge or reduce. The thumb nut 21 holding mask 11 to the guide is loosened, and the slide is moved on the guide until the edge 12 of the mask 11 comes in contact with the stop 23 and lies parallel to it; when the nut 21 is tightened, mask 11 is prevented from changing its position with reference'to the slide 18. The device is now placed over the picture it is proposed to enlarge, and by sliding mask ll along the guide 18 it is possible at a glance todetermine whether the whole picture will enlarge to the desired size, and if not, it is possible to see without any calculation just what part of the picture can most advantageously be used. With a sharp pencil the part to be used can be delimited. The device can also be used reciprocally; by setting the masks on the edges of the picture, enlarging sizes can be read off the scale at the end of the guide.

With the type of mask 11 disclosed in Figure 6, the inch scale and stop on mask 10 can be eliminated, the edges of mask 11 being adjusted perpendicular to mask l0 by setting the finger 24o on the slide 24, to positions on the scale 22h corresponding to the setting of nger 22 and scale 22a on guide 18 and mask 10 respectively.

While there is herein shown and described the preferred embodiments of the present invention, it is to be understood that changes may be made in the details of construction without departing from the spirit of the invention as shown and claimed.

I claim:

1. A proportioning device of the characterV described, comprlsing a pair of masks having cutaway portions with the two masks deiining a rectangular opening, one of the masks being slidable on the other mask, and means for guiding the slidablemask in its movements, said means compri-singk an armpositioned external of the deiined rectangular opening and pivotally mounted onA the Stationary mask, said arm forming the member onwhich the slidablernask is movable, whereby the proportions of the rectangular opening may be varied.

2. A proportional masking device of the character described comprising a pair of masks having cut-away portions with the two masks de- `iining a rectangular opening, one of the masks being slidable on the other mask, the latter being stationary, and means for guiding the slidable mask in its movements, said means comprising an arm positioned external of the dened rectangular opening and pivotally mounted on the stationary mask, whereby the proportions of the rectangular opening may be varied, and visual means for determining the proportional dimensions of the rectangular opening.

3. A proportional mask of the character described, comprising a pair of mask elements, one of which is pivotally and slidably mounted relatively to the other, and means for supporting one mask carried by the other mask, said masks being fashioned to form a rectangular opening and constructed and adapted for maintaining constant proportions during movement of one mask element, the pivotally mounted mask element being adjustable to vary the proportion of the rectangular opening, and setting means associatedwith the mask plates, said supporting means being located to prevent obstruction of the rectangular opening.

4. As a means for mechanically determining enlarging or reducing possibilities of pictorial or other matter to be presented as varied from the original dimensions, and wherein the zone being tested is in the form of a rectangle, a mask structure formed of a pair of elements each having walls producing one of the right angles of the rectangle, said elements being adjustable relatively to each other and constructed and adapted to produce the two right angles of the rectangle adjacent to such individual angles, and means for supporting one element relatively to the other to permit adjustable and relative movements therebetween with such movements including movement in the direction of a line connecting apices of the angles individual to the elements to proportionately vary the dimensions of the rectangle, said means including an arm pivoted remote from either angle apex and movable to vary the relation of said line to one of said angles.

5. As a means for mechanically determining enlarging or reducing possibilities of pictorial or other matter to be presented as varied from the original dimensions, and wherein said possibilities are based upon a selected dimensional characteristic, a mask element having a rectangular opening of fixed dimensions, a pivoted mask member having an open-sided right-angular recess the two walls of which co-operate with two of the walls of the mask element opening to produce the bounds of the rectangular sight-opening presenting the possibility, a guide member pivoted to the mask element and shiftable between selected positions, and a slide carried by the guide member and to which the mask member is pivoted, the pivot points of the guide member and mask member being respectively located relative to the opposite working angles of the mask element and mask member as to cause a line corresponding to the diagonal connecting said Working angles to extend parallel with and spaced laterally relatively to a line connecting said pivots in any of the selected positions of the guide member.

6. Means as in claim 5 characterized in that the guide member is positioned external of the sight opening in each of the selected positions, whereby the sight opening is unobstructed.

'1. Means as in claim 5 characterized in that the connections between the mask element and mask member are such that the position of the diagonal line is shiftable with the'shifting of the guide member and remains constant during shifting movements of the slide in varying the dimensions of the sight opening in any of the positions.

8. Means as in claim 5 characterized in that the mask member and slide carry co-operating means for permitting pivotal movement of the mask member to produce the right angular relation of the walls of the sight-opening when changing the position of the guide member and for retaining the mask member in such adjusted position with the guide member in a selected position.

9. Means as in claim 5 characterized in that means are provided for adjustably securing the guide member in any of its selected positions.

10. Means as in claim 5 characterized in that the mask element carries means co-operative with the mask member in adjusting the position of the latter to produce the parallelism between the diagonal line and the line connecting the pivots.

11. Means as in claim 5 characterized in that the mask element carries a guide co-operative with the mask member in adjusting the position of the latter to produce the parallelism between the diagonal line and the line connecting the pivots.

12. A proportional mask of the character described, comprising a pair of mask elements, and

means for supporting one mask element by the other with a pivotal and slidable relation therebetween, said means including an arm carried by the supporting mask element, said arm being pivoted at one end to said element to permit re1- ative pivotal movement therebetween and having means at the opposite end for adjustably securing the arm to said element at any point within a limited range of such pivotal movement, the other mask element being slidably and pivotally mounted on the arm intermediate the arm pivot point and the position of the means for adjustably securing the arm.

` ROBERT C. COOK. 

